BIO CBIO 3400 Fall 2012 Second Quiz Lechtreck Fechheimer QUESTION 1 25 POINTS DNA storage 2 pts production 2 pts a 10 Points List five cellular compartments or cell organelles Briefly describe its ultrastructural features and name its major function in keywords 1 Nucleus double membrane organelle Important for RNA transcription DNA replication and 2 Mitochondria double membrane organelle with inner membrane folded Important for energy 3 Endoplasmic reticulum single membrane organelle Important for synthesis of transmembrane and secreted proteins protein folding and protein N linked glycosylation 2 pts 4 Golgi apparatus single membrane organelle Important for protein modification O linked glycosylation M6P and sorting 2 pts 5 Lysosome Single membrane organelle Important for degradation 2 pts Or any other organelles such as plastid vacuole peroxisome proteasome ribosome etc b 5 Points How do we explain the origin of cell organelles such as mitochondria and plastids Endosymbiont hypothesis Mitochondria and plastids originate through the symbiosis of aerobic prokaryotic cells and host pre eukaryotic cells 2 pts Initially a prokaryotic cell is engulfed into a eukaryotic cell The host cell provides the outer membrane to surround the prokaryotic cells The prokaryotic cells were reduced to cell organelles such as mitochondria or plastids and lost their independence due to gene transfer in the host cell nucleus 3 pts c 5 Points List five facts supporting the theory hypothesis you described in the part b and 1 Have double membrane Inner one from the prokaryotic cell and outer one from the plasma explain why in keywords membrane of host cell 1 pt 2 Have circular DNA It s similar to prokaryotic DNA 1 pt 3 Lack histones Prokaryotic cells don t have histones 1 pt 4 Have smaller ribosome Similar to prokaryotic cells 1 pt 5 Start protein synthesis with formyl methionine Prokaryotic cells also use it to start the protein synthesis 1 pt Others such as polycistronic versus monocistronic mRNA mode of division involving Ftsz for plastids only mitochondria and plastids are phylogenetically related to prokaryotes etc d 5 Points Briefly explain the following terms in keywords nucleomorph a small reduced eukaryotic nucleus found in certain plastids 1 pt apicoplast a reduced non photosynthetic plastid found in most Apicomplexa Formed by secondary endosymbiosis It has four membranes 1 pt secondary endosymbiosis An eukaryotic cell engulfs another eukaryotic cell Eventually one is reduced to become an organelle of the host cell 1 pt stromatolites layered fossil structure formed by microorganisms such as cyanobacteria Provide the most ancient record of the life on Earth 1 pt compartmentalization rule a membrane separates a plasmatic and a non plasmatic compartment 1 pt
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